Method of and an arrangement for automatically measuring electric connections of electronic circuit arrangements mounted on printed circuit boards

ABSTRACT

A method of and an arrangement for determining electric connections at a printed circuit board between boundary-scan compliant circuit terminals of one or more boundary-scan compliant devices. An electronic processing unit retrieves properties of the or each boundary-scan compliant device and a list comprising boundary-scan cells operable as a driver and/or sensor. Based on this list, a boundary-scan cell connected to a circuit terminal is operated as a driver, and at least one other boundary-scan cell connected to another circuit terminal is operated as a sensor. Data from the boundary-scan register, comprising the driver and sensor data, is stored in a storage device. The steps of operating boundary-scan cells as driver and sensor are repeated for a plurality of cells. The data stored are analyzed for determining electric connections. A result of the analysis is presented.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is related to and claims benefit from U.S.Provisional Patent Application No. 61/484,469 filed on May 10, 2011,entitled “A method of and an arrangement for automatically measuringelectric connections of electronic circuit arrangements mounted onprinted circuit boards”, and Dutch Patent Application NL 2006759 filedon May 10, 2011, both of which are incorporated herein by reference intheir entirety.

TECHNICAL FIELD

The present disclosure relates generally to the field of measuringelectric connections of electronic circuit arrangements and, morespecifically, to automatically determining electric connections at aprinted circuit board between circuit terminals of one or moreboundary-scan compliant devices of such electronic circuit arrangement,and comparing same with a known or reference electronic circuitarrangement of the same type.

BACKGROUND OF THE DISCLOSURE

Design engineers, service repair technicians, production engineers andthe like often require a simple tool for measuring electric connectionsbetween circuit terminals or pins of components and devices of anelectronic circuit arrangement mounted on a Printed Circuit Board, PCB.

Such connection measurements can be performed using well-knownmultimeters, for example, by measuring the ohmic resistance between therespective circuit terminals. In the case of a galvanic electricconnection by an electrically conductive track on the PCB, for example,the measured resistance will be near zero ohms. In the event of a brokenconnection, for example, a resistance near infinity will be measured.

The present miniaturization of Integrated Circuits, ICs, and theintroduction of Surface Mounted Devices, SMDs, on both sides of a PCB,for example, have made it practically impossible to access the circuitterminals of such devices of an electronic circuit arrangement by themeasurement probes of a multimeter or a test bed fixture.

However, also in the design of electronic circuit arrangements mountedon present PCBs there is a genuine need for measuring connectionsbetween circuit terminals of circuit components of the electroniccircuit arrangement mounted on such PCB, in a simple and reliablemanner.

Boundary-Scan Test, BST, technology provides a tool for testingconnections between components, such as ICs, of an electronic circuitarrangement mounted on a PCB, without using physical test or measurementprobes or fixtures. In a boundary-scan compliant device, boundary scancells connect between the circuit terminals and the electronic circuitryof the device, also called the In Core Logic. The boundary-scan cellscan force and/or capture data, i.e. digital signals, at the circuitterminals of the device. The boundary-scan cells of a device are seriesconnected to form a boundary-scan register. Boundary-scan registers ofboundary-scan compliant devices at a PCB may be series connected to forma single boundary-scan chain or a plurality of boundary-scan chains.

Test Access Ports, TAP, are provided for shifting data in and out of theboundary-scan register and for applying control signals to present dataat an output of a boundary-scan cell, to capture data at an input of aboundary-scan cell, and for shifting data through the boundary-scanregister.

Several types of boundary-scan cells can be distinguished:

-   -   an input cell;    -   an output2 cell, having two possible logic output states 0 or 1;    -   an output3 cell, having three possible logic output states 0, 1        and Z (tri-state);    -   a Bi-directional cell or Input/Output cell;    -   a dot 4 cell;    -   a dot 6 cell; and    -   a control cell for enabling or disabling the driver of an        output3 cell or a bidirectional cell.

A boundary-scan cell operating for capturing data at an associatedcircuit terminal is also called a sensor and a boundary-scan celloperating for outputting data at an associated circuit terminal of aboundary-scan compliant device is also called a driver.

Boundary-scan test systems are generally comprised of two basicelements: a Test Program Generator, TPG, and the Test Execution, TE. ATPG requires a list describing the connectivity of the PCB, also callednet list, and the so-called Boundary-Scan Description Language, BSDL,files of the respective boundary-scan components mounted on the PCB.BSDL enables users to provide a description of the manner in which aparticular device is made boundary-scan compliant. The BSDL file is usedby the boundary-scan test system to make use of the device features fortest program generation and failure diagnosis.

For performing a boundary-scan measurement to gain knowledge aboutconnections between circuit terminals on a PCB, a user has to provide atest plan consisting of various test steps, including the generation oftest vectors, i.e. a well defined series of logical “1” and logical “0”bits. Developing such test vectors is time consuming, requires skilledusers and knowledge about how the circuit terminals on the PCB areconnected. Since IC's are getting more and more complex, the testprocedures become likewise more complex and take more time to becompleted. For a user, looking for a simple and reliable automaticalternative to the above-described multimeter approach for measuringconnections of an electronic circuit arrangement mounted on a PCB,present regular boundary-scan testing does not provide a genuinealternative.

SUMMARY

In a first aspect, there is provided a method of determining electricconnections at a printed circuit board between boundary-scan compliantcircuit terminals of at least one boundary-scan compliant device mountedon the printed circuit board and comprising a boundary-scan register ofboundary-scan cells connected to the circuit terminals, the method usingan electronic processing unit and comprising the steps of:

a) retrieving, by the processing unit, boundary-scan properties of theat least one boundary-scan compliant device, the properties at leastcomprising a listing of boundary-scan cells operable as a driver and/orsensor;

b) operating, by the processing unit, a boundary-scan cell connected toa circuit terminal as a driver and outputting data at the circuitterminal;

c) operating, by the processing unit, at least one other boundary-scancell connected to an other circuit terminal as a sensor for sensing datareceived at the other circuit terminal and latching the sensed data intothe boundary-scan register;

d) storing, by the processing unit, in a data storage device data fromthe boundary-scan register comprising the driver and sensor data;

e) repeating, by the processing unit, steps b)-d) for a plurality ofboundary-scan cells of the listing of boundary-scan cells;

f) analyzing, by the processing unit, the stored driver and sensor datafor determining electric connections between the circuit terminals onthe printed circuit board; and

g) presenting, by the processing unit, determined electric connectionson the printed circuit board.

The disclosure is based on the insight that circuit terminals ofboundary-scan compliant devices of an electronic circuit arrangementmounted on printed circuit board, including a single boundary-scancompliant device, between which a connection has to be tested ormeasured, are accessible through the corresponding boundary-scan cellsconnected to these circuit terminals. In the present description andclaims such circuit terminals are also called boundary-scan compliantcircuit terminals.

A skilled person will appreciate that in the event of an electricconnection between circuit terminals, data outputted by one of thecircuit terminals operated as a driver is received by an other of thecircuit terminals operated as a sensor. In the present description andthe claims, the term “electric connection” is construed as comprising agalvanic electric connection, such as an electrically conductive trackon a PCB, and/or a logic electric connection, such as provided by alogic inverter or other logic circuit of an electronic circuitarrangement mounted on a PCB logically connecting circuit terminals ofthe arrangement.

The electronic processing unit operates a boundary scan cell connectedto a circuit terminal as a driver and operates at least one othercircuit terminal as a sensor. By latching the driver and sensor data inthe boundary scan cell register and storing same in a data storage andrepeating these steps for a plurality of boundary scan cells connectedto circuit terminals of the or each boundary scan compliant device,electric connections between circuit terminals can be determined bymatching the stored driver and sensor data. A result is presentedholding information about what circuit terminals are connected on thePCB.

In the present description and the claims, the term “operate” or“operating” is to be construed in that the respective boundary-scancells are controlled to perform the operation of a driver or sensor,respectively. If a respective cell is a permanent driver or output cell,the term operating comprises controlling the respective boundary-scancell for the purpose of applying data from the boundary-scan register tothe circuit terminal associated with the driver or output cell. If arespective cell is a permanent sensor or input cell, the term operatingcomprises controlling the respective boundary-scan cell for the purposeof latching data from the circuit terminal associated with the sensor orinput cell into the boundary-scan register. In case the boundary-scancells are of the bi-directional type, operating comprises in additionenabling of a cell in the desired mode, i.e. driver or sensor,respectively.

In a basic embodiment of the present method, it suffices to drive thedriver at a circuit terminal by a logical “1” and a logical “0” or by asequence of logical ones and zeros, and to analyze whether the datacaptured by the at least one sensor at the other circuit terminal(s)follows the order in time of the signals applied by the driver. In theaffirmative, one may conclude that the circuit terminals are connected.

Different from regular boundary-scan testing, the present method doesnot require the generation of complicated test vectors for drivingcircuit terminals nor a complicated analysis of received and captureddata at circuit terminals. It will be appreciated that the output valueof boundary-scan compliant circuit terminals not operating as driver orsensor has to be kept unchanged while applying the method according tothe disclosure.

The present method can be set up and conducted very quickly. Note thatfor conducting the present method, no connectivity list or net list ofthe electronic circuit arrangement and/or the PCB is required, nor is aselection by a user required concerning which circuit terminals have tobe measured. The electronic processing unit itself may select, on thebasis of the retrieved list of boundary scan properties, whichboundary-scan compliant circuit terminals have to be included in themeasurement. That is, permanent driver cells may not be operated assensor and permanent sensor cells may not be operated as driver.

The present method can be conducted fully automatically, without theuser having to bother about test vectors. The operation of drivers andsensors may be fully automatically performed by the electronicprocessing unit itself and may follow an arbitrarily order or apre-selected measurement sequence, for example.

In an embodiment the step of operating, by the processing unit, at leastone other boundary-scan cell as a sensor for sensing data received atthe other circuit terminal and latching the sensed data into theboundary-scan register, include simultaneously selecting and operatingeach boundary-scan cell of the listing of boundary-scan cells operableas a sensor.

That is, for a particular driver selection, all boundary-scan cellsconnected to a circuit terminal, except for the boundary-scan celloperated as driver, are simultaneously operated as sensor, if applicablefrom their boundary scan properties. By analyzing the stored data,information can be presented to a user about which circuit terminal orterminals operated as a sensor electrically connect to the circuitterminal operated as a driver.

In an other embodiment, the steps of operating, by the processing unit,a boundary-scan cell connected to a circuit terminal as a driver andoutputting data at the circuit terminal; operating, by the processingunit, at least one other boundary-scan cell as a sensor for sensing datareceived at the other circuit terminal and latching the sensed data intothe boundary-scan register; and storing, by the processing unit, datafrom the boundary-scan register comprising the driver and sensor data ina data storage device, are repeated sequentially for each boundary-scancell of the listing of boundary-scan cells operable as a driver.

By sequentially operating different circuit terminal as driver and byeach time collecting and storing data sensed by the sensors, theprocessing unit, when all data for each possible driver are collected,may provide the user a complete overview of the electric connectionsbetween the circuit terminals of a particular electronic circuitarrangement.

The electronic processing unit of the embodiment holds a data storage orthe like for storing, i.e. buffering, the data latched into theboundary-scan register. Depending upon the amount of boundary-scan cellsand the size of the boundary-scan register the data storage is arrangedfor buffering an adequate amount of data. For analyzing purposes, theelectronic processing unit may access the data stored in the datastorage.

As a first test to get an indication whether boundary-scan compliantcircuit terminals are active or alive, the boundary-scan registers ofboundary-scan compliant devices may be driven in a so-called samplemode, wherein samples of the logic states or logic signal values atcircuit terminals are captured and latched in the boundary scanregister, during normal operation of the electronic circuit arrangementunder test. By analyzing the samples and if the logic state of aparticular circuit terminal does not change at all, this may be a firstindication that the respective terminal or terminals is or are notconnected, for example.

The boundary-scan properties of a particular boundary-scan compliantdevice may be retrieved from a library or data bank, such as on-lineavailable from a device manufacturer, for example, either locally orremotely accessible for the electronic processing unit. In particular, aBoundary Scan Description Language, BSDL, file of the or eachboundary-scan compliant device mounted at the PCB can be loaded in theprocessing unit, for displaying the list comprising the boundary-scancompliant circuit terminals, for selecting same and operating a driverand sensor based upon the respective BSDL file.

The BSDL file provides, among others, information about the circuitterminals of a device that are boundary-scan compliant and the types ofboundary-scan cells described above, for operating same as a driver orsensor. Further, the BSDL file provides information about the bitposition of a respective boundary-scan cell in the boundary-scanregister, among others for analyzing purposes. That is, based on thepositions of the boundary-scan cells operated as driver and sensor, thedriver and sensor data outputted by the boundary-scan register can becompared for the type of connection.

In the case of a plurality of boundary-scan compliant devices mounted ona PCB, prior to the start of a particular measurement, the position ofthe boundary-scan register of individual boundary-scan compliant devicesin a chain of series connected boundary-scan registers of the devicesmounted at the PCB has to be known to the processing unit. In a manualembodiment, the processing unit receives this information from userinput. From this information and the boundary-scan properties containedin the respective BSDL files, for example, the processing unit can formand shift a proper bit sequence through the chain for operating aselected driver and for analyzing latched data of a selected sensor. Ina fully automated version, the processing unit may receive the chaininformation from a data bank, for example.

In a further embodiment, a graphical user interface device is provided,wherein at least one of the steps of operating, analyzing and presentingare displayed on the graphical user interface device. The differentsteps and the result of the analysis by the electronic processing unitmay be visualized to a user in a number of different manners.

In an example, a listing or table of circuit terminals of the at leastone boundary-scan compliant device and electric connections between thecircuit terminals determined as a result of the analyzing of the storeddriver and sensor data may be presented.

In an other example, a circuit diagram representation may be presented,graphically indicating the at least one boundary-scan compliant devicewith its circuit terminals and electric connections between the circuitterminals determined as a result of the analysis of the stored driverand sensor data.

In an alternative further embodiment, a manual selection of a pluralityof circuit terminals for determining electric connections is provided.To this end the graphical user interface device, in a very easy andintuitive manner, not requiring special skilled knowledge, is controlledby the electronic processing unit such to select a plurality of circuitterminals indicated by a user from a displayed list of boundary-scancompliant circuit terminals. This selection may be displayed by thegraphical user interface device before receiving same by the electronicprocessing unit for further processing of the connections measurement.The graphical user interface device can be even further enhanced in thatthe activation or operation, i.e. the data outputting by the driverand/or the data sensing by the sensor can be controlled from suchgraphical user interface device. The user may select particular testdata to be applied at the driver through the boundary scan register of arespective boundary-scan compliant device. The analysis result may bepresented using the graphical user interface device.

Boundary scan cells of a boundary-scan compliant device not operating asa driver or sensor may be disabled, if applicable, by setting same in atri-state Z mode, for example, and/or rendered non-operative by use of aBYPASS instruction to the boundary-scan compliant device, bypassing thecomplete boundary-scan register of a boundary-scan device that not takespart in the connections measurement. The disabling of boundary-scancells may be controlled from the graphical user interface, for example,or by the electronic processing unit itself from the retrievedproperties of the boundary-scan compliant devices. As described above,output3 cells and bidirectional cells may be disabled by a control cell.

For release purposes, for example, one may beforehand identifymalfunctioning of the electronic circuit arrangement caused by improperterminal connections by comparing the measurement results of aparticular electronic circuit arrangement with identical measurementsperformed at a known or reference electronic circuit arrangement of thesame type. For repair purposes, like measurements can be performed todetermine broken or short-circuit connections, for example.

In a further embodiment, also called a compare mode, the determinedelectric connections at the printed circuit board and electricconnections at a reference printed circuit board are compared by theprocessing unit and a result of the comparison of connections betweenthe printed circuit boards is presented.

In this compare mode, determined electric connections at a PCB of anelectronic circuit arrangement under test are compared with knownelectric connections at a reference PCB of a reference electroniccircuit arrangement of the same type as the electronic circuitarrangement under test. In this manner, for example, deviations betweenthe PCB under test and the reference PCB can be indicated, therebyproviding an effective tool for fault measurement or release of circuitarrangements.

Those skilled in the art will appreciate that, with the method of thepresent disclosure, in a so-called learning mode, initially the electricconnections at the PCB of a correct operating electronic circuitarrangement can be determined. The thus determined electric connectionsare then stored and used as reference data for comparing further circuitarrangements and PCBs under test.

In a further aspect, there is provided an arrangement for determiningelectric connections at a printed circuit board between boundary-scancompliant circuit terminals of at least one boundary-scan compliantdevice mounted on the printed circuit board and comprising aboundary-scan register of boundary-scan cells connected to the circuitterminals, the arrangement comprising an electronic processing unit,wherein the electronic processing unit is arranged for:

-   -   retrieving boundary-scan properties of the at least one        boundary-scan compliant device, the properties at least        comprising a listing of boundary-scan cells operable as a driver        and/or sensor;    -   operating a boundary-scan cell connected to a circuit terminal        as a driver and outputting data at the circuit terminal;    -   operating the at least one other boundary-scan cell connected to        an other circuit terminal as a sensor for sensing data received        at the other circuit terminal and latching the sensed data into        a boundary-scan register;    -   storing, in a data storage device, data from the boundary-scan        register comprising the driver and sensor data;    -   repeating the operating and outputting, operating and latching        and storing for a plurality of boundary-scan cells of the        listing of boundary-scan cells;    -   analyzing the stored driver and sensor data for determining        electric connections between the circuit terminals at the        printed circuit board; and    -   presenting determined electric connections between circuit        terminals at the printed circuit board.

As described above, the electronic processing unit may automaticallyoperate boundary-scan cells as driver and/or sensor, either randomly orin accordance with a particular selection scheme.

In a further embodiment the present arrangement comprises a graphicaluser interface device operatively connected to the electronic processingunit at least arranged for presenting the result of at least one of thesteps of retrieving boundary-scan properties of the at least oneboundary-scan compliant device, operating a boundary-scan cell as adriver, operating at least one other boundary-scan cell as sensor andanalyzing and presenting a result of the driver and sensor data.

The arrangement further comprises input means for inputting boundaryscan properties of boundary scan compliant devices, such as BSDL files,and for inputting user data such as control signals, a particularplurality of circuit terminals for determining electric connections, andthe like.

The present method may be executed by an electronic processing devicethrough a control interface for controlling the boundary-scan logic.Such control interfaces are known and commercially available fromapplicant.

The arrangement, in an embodiment, further comprises a controlinterface, electronically connected to the electronic processing devicefor controlling the boundary-scan logic and the data storage device forstoring, i.e. buffering, data of the boundary scan register.

In another aspect, the disclosure also provides a computer programproduct comprising a computer program having program code data stored ona data carrier and arranged for performing the present method, when theprogram code data are loaded into a memory of an electronic processingunit or device and are executed by the electronic processing unit.

Advantageously, this computer program product may be comprised by any ofa group of data carrying devices including floppy discs, CD-ROMs, DVDs,tapes, memory stick devices, zip drives, flash memory cards, remoteaccess devices, hard disks, semi-conductor memory devices, programmablesemi-conductor memory devices, optical disks, magneto-optical datastorage devices, ferro electric data storage devices and electrical andoptical signal carriers or any other type of data carrier, having theprogram code data stored thereon.

The above-mentioned and other features and advantages of the disclosureare illustrated in the following description with reference to theenclosed drawings which are provided by way of illustration only andwhich are not limitative to the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows, in a schematic and illustrative manner, a typical priorart boundary-scan compliant electronic device.

FIG. 2 shows, in a schematic and illustrative manner, a typical priorart boundary-scan cell.

FIG. 3 shows, in a schematic and illustrative manner, an electroniccircuit arrangement mounted on a printed circuit board as a device undertest connected to a test arrangement for performing a connectionsmeasurement according to the present disclosure.

FIG. 4 shows, in a schematic and illustrative manner, a flow chartdiagram illustrating the steps of an embodiment of the method inaccordance with the disclosure.

FIG. 5 shows, in a schematic and illustrative manner, a flow chartdiagram illustrating the steps of a further embodiment of the method inaccordance with the disclosure.

FIG. 6 shows, in a very schematic and illustrative manner, a graphicaluser interface for use with the present disclosure.

FIG. 7 shows, in a schematic and illustrative manner, an embodiment of atest arrangement for performing a connections measurement according tothe present disclosure, connected to a printed circuit board.

DETAILED DESCRIPTION

FIG. 1 shows an embodiment of a boundary-scan compliant device 10comprising a housing 11 provided with supply terminals 12, 13 forpowering electronic circuitry or In Core Logic 16. The housing 11comprises a plurality of circuit terminals 14, also called boundary-scancompliant circuit terminals, connected via boundary-scan cells 15 to theIn Core Logic 16. In this embodiment the housing 11 is of a typicalSurface-Mounted Device, SMD type. The boundary-scan cells 15 togetherform a boundary-scan register 17 in which data is shifted from a TestData Input, TDI 18, via the different boundary-scan cells 15, to a TestData Output, TDO 19. The different boundary-scan parts are controlled bya Test Access Port controller, TAP 20, having at least a Test ModeSelect Input, TMS 21, and a Test Clock Input, TCK 22. The TAP controller20 is controlled in a way well-known to those skilled in the art anddefined by boundary-scan standards, such as IEEE STD 1149.1 and higher.

FIG. 2 schematically shows a generalized representation of aboundary-scan cell, BSC, 25, having an input 26 and an output 27. Theboundary-scan cell 25 may operate as a sensor for sensing and capturinglogic signals at a circuit terminal of the boundary-scan compliantdevice. To this end the input 26 is connected to a circuit terminal 14,as shown in FIG. 1. The output of the boundary-scan cell 27 thenconnects to the In Core Logic 16. The boundary-scan cell 25 may alsooperate as a driver for outputting a logic signal at a circuit terminalof the boundary-scan compliant device. To this end the input 26 isconnected to the In Core Logic 16 and the output 27 is connected to acircuit terminal 14.

The boundary-scan cell 25 can either be a permanent driver, a permanentsensor or of a bi-directional type. When being bi-directional, the modeof the boundary-scan cell 25 (i.e. driver or sensor) is controlled fromthe TAP controller 20 by a boundary-scan cell operating as a controlcell (not shown). Capturing data at the input and forcing data at theoutput of the cell 25 are also controlled from the TAP controller 20, ina standardized manner, as known to the skilled person. Output 28 andinput 29 of the boundary-scan cell 25 are register connections forconnecting to a corresponding neighbouring boundary-scan cell input 29and output 28, respectively. Boundary-scan cells series connected inthis way form the boundary-scan shift register 17, as shown in FIG. 1.

FIG. 3 shows an example of a Printed Circuit Board, PCB, 31 with fourboundary-scan compliant devices 32, 33, 34, 35 constituting anelectronic circuit arrangement. The boundary-scan registers of thedevices 32, 33, 34, 35 are series connected and form a boundary-scanchain 44, controlled from a control interface or boundary scancontroller 43. The controller 43 is, in general, a control interfacedevice separate from the PCB 31. However, as illustratively shown inbroken lines, the controller 43 may also be mounted at the PCB 31. Thecontroller 43 operates the TAP controllers 30 of the boundary-scancompliant devices 32, 33, 34, 35.

FIG. 3 shows several electric connections at the PCB 31, such as theelectric connections 36, 39 between different boundary-scan compliantcircuit terminals 37, 38 and 40, 41, respectively. Such electricconnections, in general, are formed by electric conductive tracks at thePCB. Although not illustrated, the PCB 31 may also comprise electricconnections between boundary-scan compliant circuit terminals of one andthe same boundary-scan compliant device 32, 33, 34, 35. Those skilled inthe art will appreciate that in practice a PCB 31 comprises a pluralityof connections 36, 39 either direct or galvanic connections and/orlogical connections.

Assume a user would like to test connection 36, connecting boundary-scancompliant circuit terminal 37 of the boundary-scan compliant device 32and boundary-scan compliant circuit terminal 38 of the boundary-scancompliant device 33, as well as connection 39, connecting boundary-scancompliant circuit terminal 40 of the boundary-scan compliant device 34and boundary-scan compliant circuit terminal 41 of boundary-scancompliant device 35. Note that the connections 36 and 39 need not beknown beforehand.

Using prior art boundary-scan test methods and equipment, for testingthe connections 36, 39 a complex set of test vectors has to bedeveloped, executed and analyzed.

As will be illustrated in detail with reference to FIG. 4, with a testor measurement arrangement 42 according to the present disclosure, theconnections 36, 39 can be tested in an intuitive and easy-to-use manner.The arrangement 42, comprising an electronic processing unit or device,operates in conjunction with the controller 43, using standardizedboundary-scan control instructions. For the purpose of the presentdisclosure these control instructions are regarded as known to theperson skilled in the art of boundary-scan and are not repeated here.

It will be appreciated that the boundary scan controller 43 may also beincorporated in the test arrangement 42, or on the PCB 31, asillustratively shown by broken lines.

FIG. 4 shows steps of an example embodiment for determining electricconnections on the PCB 31 as shown in FIG. 3 by the test arrangement 42in accordance with an example of the present disclosure. For determiningconnections such as 36 and 39, in a first step 46, “Retrievingboundary-scan properties”, boundary-scan properties of the or eachboundary-scan compliant device 32, 33, 34, 35 mounted at the PCB 31 areretrieved by the electronic processing unit of the test arrangement 42.The properties at least comprise a listing of boundary-scan compliantcircuit terminals of the boundary-scan compliant device(s) 32, 33, 34,35. The properties further comprise information regarding the type ofboundary-scan cells connected to the boundary-scan compliant circuitterminals of the boundary-scan compliant device(s) 32, 33, 34, 35. Withthis type information of the boundary-scan cells the test arrangement 42can at least determine whether a boundary-scan cell is operable as adriver, operable as a sensor or as both, i.e. bi-directional.

The respective properties can be retrieved automatically by theprocessing unit of the arrangement 42, based on prior knowledge of aparticular PCB 31, i.e. the type or types of boundary-scan compliantdevices 32, 33, 34, 35 mounted thereon, or from a manual user input ofthe several types of boundary-scan compliant devices 32, 33, 34, 35mounted at the PCB 31. Having the type information of the devices, theirrespective boundary scan properties can be retrieved from a library ordata bank, such as on-line available from a device manufacturer, forexample, either locally or remotely accessible for the electronicprocessing unit of the arrangement 42. In particular, a Boundary ScanDescription Language, BSDL, file of the or each boundary-scan compliantdevice mounted at the PCB can be loaded in the processing unit.

For shifting a suitable bit sequence through the boundary scan registersof the boundary-scan compliant devices 32, 33, 34, 35, the processingunit of the test arrangement 42 has to know the position of the severaldevices 32, 33, 34, 35 in the chain of series connected boundary-scanregisters. Likewise, for analyzing purposes, the processing unit mustknow the position of latched data of a selected sensor in the chain ofseries connected boundary-scan registers. This information may beprovided manually by a user having knowledge of the PCB 31 or theinformation may be electronically available from a data bank comprisingsuch information of a particular PCB or electronic circuit arrangement,for example.

In a second step 47, “Operate boundary-scan cell as driver and outputdata”, a boundary-scan cell of the list of boundary-scan cells formed bythe step 46 of retrieving boundary-scan properties, is operated as adriver such that data is outputted at the circuit terminal connected tothe selected boundary-scan cell. The test arrangement 42 itselfautomatically selects a boundary-scan cell to be operated as a driverbased on a random pick from the list of boundary-scan cells or, forexample, based on the first boundary-scan cell of the list operable as adriver, or any other predetermined sequence.

In an alternative embodiment, a user of the test arrangement 42 maydecide which circuit terminal should be tested so which therewithconnected boundary-scan cell is to be operated as a driver, presumingthe boundary-scan cell is operable as a driver and not, for examplesolely as a sensor.

For outputting data, the driver is controlled for providing a logicalsignal, such as a logical “1”, a logical “0” or combinations of logicalone's and zero's at its connected circuit terminal, such as terminal 37.The data for outputting by the driver are supplied to the respectiveboundary-scan cell operated as driver via the boundary-scan registerunder control of the boundary-scan controller 43, the TAP control logicof a particular device and the electronic processing unit of the testarrangement 42.

In step 48, “Operate at least one other boundary-scan cell as sensor”,boundary-scan cell(s) which are operable as sensor are operated assensor(s) by the processing unit of the test arrangement 42 forcollecting data in response to the data outputted by the driver. Atleast a single boundary-scan cell is to be operated as a sensor, whichfor example in FIG. 3 could be the boundary-scan cell connected to thecircuit terminal 38, assuming this boundary-scan cell is of a typeoperable as a sensor.

In a further embodiment a plurality of boundary-scan cells are operatedas sensor and in another embodiment all boundary-scan cells of theboundary-scan compliant devices 32, 33, 34, 35 of the PCB 31 operable asa sensor are simultaneously operated as a sensor.

The term “operate” is to be construed in that the respectiveboundary-scan cells are controlled to perform the operation of an outputor input cell, respectively a driver or sensor. If a respective cell isa permanent output cell, then the operating step 47 comprises selectingand controlling of the respective boundary-scan cell for the purpose ofapplying data from the boundary-scan register to the circuit terminalassociated with the output cell. If a respective cell is a permanentinput cell, then the operating step 49 comprises selecting andcontrolling the respective boundary-scan cell for the purpose oflatching data from the circuit terminal associated with the input cellinto the boundary-scan register. In case the boundary-scan cells are ofthe bi-directional type, the operating steps 46 and 48 in additioncomprise enabling of a cell in the desired mode, i.e. driver or sensor,respectively.

At the next step 49, “Latch data at sensor”, data sensed by one or moresensor(s) at one or more circuit terminal(s) connected therewith arelatched in the boundary-scan register at the position determined by theselected sensor boundary-scan cell, under control of the boundary-scancontroller 43 and the electronic processing unit of the test arrangement42.

Further, in step 50, “Store driver and sensor data”, the data comprisingthe sensor and driver data obtained from the boundary-scan register 44are stored in a data storage device 45. The data storage device 45 maybe integrated in the boundary-scan controller 43 or the test arrangement42 itself or both. In FIG. 3 the data storage device 45 is indicated asa separate device accessible by the test arrangement 42. By storing datafrom the boundary-scan register 44, all data regarding the circuitterminals responding to the circuit terminal connected with theboundary-scan cell operated as a driver, i.e. the driver and sensordata, are stored for further processing by the test arrangement 42.

For completely determining the electric connections on the PCB 31, inaccordance with the disclosure, steps 47, 48, 49 and 50 are repeated bythe test arrangement 42, i.e. the processing unit thereof, for aplurality of boundary-scan cells of the listing of boundary-scan cells.This as indicated by step 51, “repeat steps 47-50”.

For example, in an embodiment of the method according to the disclosure,a series of measurements or tests can be applied automatically on theelectronic circuit arrangement at the PCB 31 by the test arrangement 42.The series of tests may comprise a batch of all boundary-scan cellsoperable as a driver to be operated as a driver subsequently. For eachboundary-scan cell operated as a driver all data of respondingboundary-scan cells operable as a sensor are simultaneously latched intothe data storage. The test arrangement 42 then, after or during themeasurements, analyses the data forming a total result of all driver andsensor data, holding information about all connections on the PCB 31 ofthe boundary-scan compliant devices.

In step 52, “Analyze driver and sensor data”, at least the captured dataretrieved from the boundary scan-register are analyzed by the processingunit of the test arrangement 42, for connections between driver(s) andsensor(s). The analyzing of the data may be a logical comparison of bothdriver and sensor data, i.e. at least a logic high value 1 and a logiclow value 0. If both data are equal, one may validly conclude that bothcircuit terminals 37, 38 are connected, either by a direct or galvanicconnection 36 or theoretically also by a non-inverting logic connection.If the driver data and the sensor data are inverted, one may concludethat the connection 36 is an inverting connection. If the driver andsensor data are not equal, for example no corresponding data are latchedfrom the sensor, the connection 36 is in error or absent, for example.

As an advantage over a multimeter measurement, the present method isable to measure both a galvanic electric connection and a logic electricconnection formed by logic circuits of the electronic circuitarrangement mounted on the PCB.

For analyzing the data latched by a sensor, each time a driver outputsignal, i.e. a logic “1” or a logic “0” signal, is provided theboundary-scan register or the boundary-scan chain 44 may be completelyread and analyzed.

Note that operating a cell as driver via the TAP controller of aboundary-scan compliant device may result in operating other cells asdriver too. Likewise, operating a selected cell as sensor may result inlatching data at other cells operating as sensor. In such a case, theprocessing unit is arranged to shift a sequence of data bits through thechain of boundary-scan registers such that only the output of theboundary-scan cell operated as a driver changes its value, from logic 0to logic 1 or the other way around, for example. By knowing the bitposition of a sensor or the sensors, the processing unit can select thevalues latched by the respective sensor or sensors.

Those skilled in the art will appreciate that the bits shifted throughthe chain of boundary-scan registers may be selected such to keep othernon-boundary-scan compliant devices or components mounted at the PCB andin connection with circuit terminals of a particular boundary-scancompliant device, such as buffers or the like, in a safe mode ofoperation, for example disabled. This to avoid driver conflicts whileoperating the selected driver or drivers by the processing unit.

Alternatively, to test connections between boundary-scan compliantcircuit terminals that connect by a so-called active transparentelectrical component or device, such as a buffer or the like, of whichthe output signal equals the input signal, i.e. there is no alterationof the data by the transparent component or device, the bits shiftedthrough the chain of boundary-scan registers may be selected and set bythe processing unit to enable such transparent device. That is, toprovide that the driver data of the selected driver is transported orshifted through the transparent device towards a sensor.

In a further embodiment, use can be made of a so-called dot 6boundary-scan cell as driver, operating in a so-called toggle mode, inwhich a pulse or a pulse train of logical signals is outputted once thedriver is triggered by a logic signal in the boundary-scan register ofwhich the respective driver forms part of. By a so-called dot 6 receivercell, a rising and/or falling signal edge of a respective pulse can bedetected, thereby providing the possibility of measuring capacitiveconnections formed by a capacitor that intentionally connects selectedcircuit terminals or unintentionally by a defect at the PCB. The seriesof logic 1 and logic 0 signals outputted in the toggle mode can be set.If the set driver output data are known, the latched sensor data can beanalyzed for a connection based on this known driver data. A dot 6receiver as sensor may operate with a dot 1 driver, for example.

In step 53, “Present result”, the results of the analysis are presentedby the arrangement 42, showing what connections are present from aspecific circuit terminal used in the test, i.e. by operating itstherewith connected boundary-scan compliant circuit terminal as adriver, or, in a further embodiment even showing all connections presenton the PCB 31. The above test may be fully automated executed by thetest arrangement 42, because for a simple connections test in principalno special test vector has to be generated. Such a fully automated,without input from the user, applied test by the test arrangement 42,can present the result of all connections of the PCB 31 determined bythe test arrangement 42. The user only has to decide at what time thetest arrangement should start the test and the fully automated test isexecuted, then, without further input from the user, the results of thetest are presented to him/her.

FIG. 5 shows steps of an example embodiment of so-called learning andcomparing modes, for comparing PCBs. For this, the method according tothis example embodiment uses an electronic processing unit in a testarrangement similar to, or the same as, the test arrangement 42 shown inFIG. 3. The method compares connections of individual PCBs by applyingthe steps of determining connections according to the previouslydisclosed example embodiment, explained by the steps 46 to 53 of FIG. 4.These steps 46-53 are in step 54 of FIG. 5, “determining connections ofa reference PCB” applied to a PCB which is selected by a user tofunction as a reference PCB comprising an electronic circuit arrangementof a type similar to an electronic circuit at the PCB to be tested.

The results as presented in step 53 of the embodiment disclosed by FIG.4 are stored in step 55 of FIG. 5, “storing determined connections ofthe reference PCB”. These results can be stored in a data storagedevice, such as the data storage device 45, for example, especiallypreserved for applying this step of the method or a data storage alreadypresent in the test arrangement. The stored results comprise informationabout what electric connections are present at the reference PCB and areactually functional.

In the example embodiment as shown by FIG. 5, in the learning mode, auser selects which PCB is to be used as the reference PCB, i.e. a PCBand electronic circuit arrangement of which he/she knows is fullyoperational, in other words, fault-free. In step 56, “determineconnections of a further PCB”, in the comparing mode, a further PCB istested according to the steps 46-53 disclosed in FIG. 4. The results ofthis test comprises information about what connections are present onthis further PCB. These determined connections, i.e. the outcome of step53 of FIG. 4, are then in step 57, “storing determined connections offurther PCB” stored in the data storage according to step 55.

The processing unit of the test arrangement then, in step 58, “comparingstored connections of reference PCB with further PCB”, compares theresults of the further PCB obtained in step 56 with the results of thereference PCB obtained in step 54. During this step the test arrangementcan provide the user of the test arrangement with a signal indicativefor a correct or an incorrect operation of the further PCB. For examplethe test arrangement can comprise a visual or auditive indication forthe user when the tested further PCB's connections between the circuitterminals do not match the connections of the reference PCB'sconnections between the circuit terminals. This is an indication for aPCB having faulty connections. This result is, in step 59, “presentingresult” presented to the user.

The method described with reference to FIG. 5 may form part of anacceptance or release test of an electronic circuit arrangement or maybe performed as a step in a repair process of an electronic circuitarrangement, for example.

In FIG. 6 a Graphical User Interface, GUI, device 60, of the arrangement42, for example a computer display, is shown. The GUI 60 comprises afirst input field 61, indicating from a list 65 comprising boundary-scancompliant circuit terminals of the boundary-scan compliant devices acircuit terminal of a boundary-scan compliant device operated as adriver, and a second input field 62 for operating one or more circuitterminal(s) of a boundary-scan compliant device as a sensor. Ifrequired, in a manual operation, data to be outputted by the driver canbe set at field 63.

The result of the measurements or test is shown within the presentationfield 64 and/or acoustically signaled. The result may be displayed inthe form of circuit diagram representation and/or a list or table ofconnected circuit terminals and comprises information about aconnection, more connections or all connections of a single PCB. Theresult may, when operative in an example embodiment as shown by thesteps 54-59 of FIG. 5, further display whether the connections of thetested PCB are equal to the reference PCB or where they differ.

All selecting and execution of a test or measurement can be done by useof an input device, such as keyboard or mouse operatively connected tothe arrangement 42, comprising a digital processing unit, as generallyknown to the person skilled in the art.

Boundary scan cells not operating as a driver or sensor may be disabled,if applicable, and if possible without affecting a selected driver orsensor, by setting same in tri-state Z mode, or made non-operative byuse of a suitable instruction to the TAP controller of the boundary-scancompliant devices, bypassing the complete boundary-scan register of aboundary-scan device that not takes part in the connections measurement.The disabling of boundary-scan cells may be controlled from thegraphical user interface, controlling the TAP controller of the device,for example. As described above, output3 cells and bidirectional cellsmay be disabled by a control cell.

In particular, information regarding the boundary-scan properties ofboundary-scan compliant devices can be retrieved from the Boundary ScanDescription Language, BSDL, file of a boundary-scan compliant devicemounted at the PCB. The information of the BSDL files is also used forthe GUI 60, to visualize the several fields, as discussed.

The disclosure can be performed by a suitable programmed electronicprocessing unit taking the form of an electronic computer device and acomputer program product comprising a computer program in the form ofcode data stored on a data carrier and arranged for performing themethod disclosed, if loaded into a working memory of the electronicprocessing device.

The computer program product may comprise, but is not limited to, any ofa group of data devices including floppy discs, CD-ROMS, DVDs, tapes,memory stick devices, zip drives, flash memory cards, remote accessdevices, hard disks, semi-conductor memory devices, programmablesemi-conductor memory devices, optical disks, magneto-optical datastorage devices, ferro electric data storage devices, optical signal,electric signal and magnetic carriers and the like.

FIG. 7 shows the PCB 31 connected, for example, by a bus 71 to anarrangement 70 according to the disclosure. The arrangement 70 comprisesan electronic Central Processing Unit, CPU, 72 like a computer ormicro-processor or the like, operatively connected to an operating unit73 for operating a boundary-scan cell connected to a circuit terminal ofa boundary-scan compliant device as a driver and for selecting andoperating at least one other boundary-scan cell connected to an othercircuit terminal of a boundary-scan compliant device as a sensor. Asupply unit 74 for supplying data to the boundary-scan cell operating asthe driver. A latching unit 75 for latching data sensed by the at leastone sensor. An analyzing unit 77 for analyzing the driver and sensordata for a electric connection between the circuit terminals, and apresentation unit 78 for presenting a result of the analyzing of thedriver and sensor data. The arrangement further comprises a data storagedevice 81, for storing the data comprising the driver and sensor datafrom the boundary-scan register.

The arrangement 70 further comprises an acoustic signaling unit oraudio/visual signaling unit 79, an Input/Output unit 80, among othersfor loading BSDL files, and Graphical User Interface, GUI, device 76,for presenting measurement or test results and selecting drivers andsensors, in accordance with the embodiments described above.

Based on the above description, a skilled person may providemodifications and additions to the method and arrangement disclosed,which modifications and additions are all comprised by the scope of theappended claims.

1. A method of determining electric connections at a printed circuitboard between boundary-scan compliant circuit terminals of at least oneboundary-scan compliant device mounted on said printed circuit board andcomprising a boundary-scan register of boundary-scan cells connected tosaid circuit terminals, said method using an electronic processing unitand comprising the steps of: a) retrieving, by said processing unit,boundary-scan properties of said at least one boundary-scan compliantdevice, said properties at least comprising a listing of boundary-scancells operable as a driver and/or sensor; b) operating, by saidprocessing unit, a boundary-scan cell connected to a circuit terminal asa driver and outputting data at said circuit terminal; c) operating, bysaid processing unit, at least one other boundary-scan cell connected toan other circuit terminal as a sensor for sensing data received at saidother circuit terminal and latching said sensed data into saidboundary-scan register; d) storing, by said processing unit, in a datastorage device data from said boundary-scan register comprising saiddriver and sensor data; e) repeating, by said processing unit, stepsb)-d) for a plurality of boundary-scan cells of said listing ofboundary-scan cells; f) analyzing, by said processing unit, said storeddriver and sensor data for determining electric connections between saidcircuit terminals on said printed circuit board; and g) presenting, bysaid processing unit, determined electric connections at said printedcircuit board.
 2. The method of claim 1, wherein said step of operating,by said processing unit, at least one other boundary-scan cell connectedto an other circuit terminal as a sensor for sensing data received atsaid other circuit terminal and latching said sensed data into saidboundary-scan register includes simultaneously operating eachboundary-scan cell of said listing of boundary-scan cells operable as asensor.
 3. The method of claim 1, wherein said step of repeatingcomprises repeating steps b)-d) sequentially for each boundary-scan cellof said listing of boundary-scan cells operable as a driver.
 4. Themethod of claim 1, wherein said boundary-scan properties are retrievedfrom a Boundary Scan Description Language, BSDL, file of said at leastone boundary-scan compliant device.
 5. The method of claim 1, furthercomprising a graphical user interface device, wherein at least one ofsaid steps of operating, analyzing and presenting are displayed on saidgraphical user interface device.
 6. The method of claim 1, wherein saidstep of presenting comprises providing a list of circuit terminals ofsaid at least one boundary-scan compliant device and electricconnections between said circuit terminals determined as a result ofsaid analyzing of said stored driver and sensor data.
 7. The method ofclaim 1, wherein said step of presenting comprises providing a circuitdiagram representation graphically indicating circuit terminals of saidat least one boundary-scan compliant device and electric connectionsbetween said circuit terminals determined as a result of said analyzingof said stored driver and sensor data.
 8. The method of claim 1, whereinboundary-scan cells of at least one boundary-scan compliant device notoperated as driver or sensor are disabled separately and/or by use of aBYPASS instruction of said boundary-scan compliant devices.
 9. Themethod of claim 1, further comprising comparing, by said processingunit, said determined electric connections at said printed circuit boardand electric connections at a reference printed circuit board andpresenting, by said processing unit, a result of said comparison ofconnections between said printed circuit boards.
 10. An arrangement fordetermining electric connections at a printed circuit board betweenboundary-scan compliant circuit terminals of at least one boundary-scancompliant device mounted on said printed circuit board and comprising aboundary-scan register of boundary-scan cells connected to said circuitterminals, said arrangement comprising an electronic processing unit,wherein said electronic processing unit is arranged for: retrievingboundary-scan properties of said at least one boundary-scan compliantdevice, said properties at least comprising a listing of boundary-scancells operable as a driver and/or sensor; operating a boundary-scan cellconnected to a circuit terminal as a driver and outputting data at saidcircuit terminal; operating at least one other boundary-scan cellconnected to an other circuit terminal as a sensor for sensing datareceived at said other circuit terminal and latching said sensed datainto a boundary-scan register; storing, in a data storage device, datafrom said boundary-scan register comprising said driver and sensor data;repeating said operating and outputting, operating and latching andstoring for a plurality of boundary-scan cells of said listing ofboundary-scan cells; analyzing said stored driver and sensor data fordetermining electric connections between said circuit terminals at saidprinted circuit board; and presenting determined electric connectionsbetween circuit terminals at said printed circuit board.
 11. Thearrangement of claim 10, comprising a data storage device operativelyconnected to said electronic processing unit.
 12. The arrangement ofclaim 10, further comprising a graphical user interface deviceoperatively connected to said electronic processing unit.
 13. Thearrangement of claim 10, further comprising input means for inputtingboundary scan properties of boundary scan compliant devices, such asBSDL files, and for inputting user data.
 14. The arrangement of claim10, wherein said electronic processing unit is arranged for comparingsaid determined electric connections at said printed circuit board andelectric connections at a reference printed circuit board and forpresenting a result of said comparison of electric connections betweensaid printed circuit boards.
 15. A computer program product comprising adata storage device storing computer program code data arranged forperforming the method of claim 1, when said program code data are loadedinto a memory of an electronic processing unit and are executed by saidelectronic processing unit.